# Social and Information Sciences Laboratory (SISL) Seminar

*,*Assistant Professor of Economics and Mathematics

*,*Caltech

*,*

Abstract: May's Theorem (1952), a celebrated result in social choice, provides the foundation for majority rule. May's crucial assumption of symmetry, often thought of as a procedural equity requirement, is violated by many choice procedures that grant voters identical roles. We show that a modification of May's symmetry assumption allows for a far richer set of rules that still treat voters equally, but have minimal winning coalitions comprising a vanishing fraction of the population. We conclude that procedural fairness can coexist with the empowerment of a small minority of individuals. Methodologically, we introduce techniques from group theory and illustrate their usefulness for the analysis of social choice questions.

Written with Laurent Bartholdi, Wade Hann-Caruthers, Maya Josyula and Leeat Yariv.

**NOTE: Location changed from Baxter 125 to Baxter B125.**